Bare fiber adapter

The Bullet® Bare Fiber Adapter is used to temporarily connect to bare (unterminated) fiber to meet test, service and communications requirements. Fiber Plus International offers the largest selection of Bullet® Bare Fiber Adapter connector styles on the market. The Bullet® features a unique holding mechanism which clamps down onto the fiber to hold it secure during testing or polishing.


A fiberscope is a flexible fiber optic bundle with an eyepiece at one end, and a lens at the other. It is used for inspection work, often to examine small components in tightly packed equipment, when the inspector cannot easily access the part requiring inspection.

The lens is often a wide-angle lens, and the eyepiece is occasionally instead connected to a camera. Some fiberscopes use an additional fiber to carry light from an external source to illuminate the material being inspected, for clearer viewing.

All fiberscopes introduce a certain amount of image distortion; much of this is similar to the distortion of modern night vision equipment.
Quartz fiberscopes can reach lengths of up to about 90 m (300 ft)[1]

Fiberscopes are used in medicine, machining, computer repair, espionage, locksmithing, safecracking, and computer forensics, among many other uses.

Optical time-domain reflectometer or OTDR

An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. An OTDR injects a series of optical pulses into the fiber under test. It also extracts, from the same end of the fiber, light that is scattered (Rayleigh backscatter) or reflected back from points along the fiber. (This is equivalent to the way that an electronic time-domain reflectometer measures reflections caused by changes in the impedance of the cable under test.) The strength of the return pulses is measured and integrated as a function of time, and is plotted as a function of fiber length.


An OTDR may be used for estimating the fiber’s length and overall attenuation, including splice and mated-connector losses. It may also be used to locate faults, such as breaks, and to measure optical return loss. To measure the attenuation of multiple fibers, it is advisable to test from each end and then average the results, however this considerable extra work is contrary to the common claim that testing can be performed from only one end of the fiber.

In addition to required specialized optics and electronics, OTDRs have significant computing ability and a graphical display, so they may provide significant test automation. However, proper instrument operation and interpretation of an OTDR trace still requires special technical training and experience.

OTDRs are commonly used to characterize the loss and length of fibers as they go from initial manufacture, through to cabling, warehousing while wound on a drum, installation and then splicing. The last application of installation testing is more challenging, since this can be over extremely long distances, or multiple splices spaced at short distances, or fibers with different optical characteristics joined together. OTDR test results are often carefully stored in case of later fiber failure or warranty claims. Fiber failures can be very expensive, both in terms of the direct cost of repair, and consequential loss of service.

OTDRs are also commonly used for fault finding on installed systems. In this case, reference to the installation OTDR trace is very useful, to determine where changes have occurred. Use of an OTDR for fault finding may require an experienced operator who is able to correctly judge the appropriate instrument settings to locate a problem accurately. This is particularly so in cases involving long distance, closely spaced splices or connectors, or PONs.

OTDRs are available with a variety of fiber types and wavelengths, to match common applications. In general, OTDR testing at longer wavelengths, such as 1550 nm or 1625 nm, can be used to identify fiber attenuation caused by fiber problems, as opposed to the more common splice or connector losses.

The optical dynamic range of an OTDR is limited by a combination of optical pulse output power, optical pulse width, input sensitivity, and signal integration time. Higher optical pulse output power, and better input sensitivity, combine directly to improve measuring range, and are usually fixed features of a particular instrument. However optical pulse width and signal integration time are user adjustable, and require trade-offs which make them application specific.

A longer laser pulse improves dynamic range and attenuation measurement resolution at the expense of distance resolution. For example, using a long pulse length, it may possible to measure attenuation over a distance of more than 100 km, however in this case an optical event may appear to be over 1 km long. This scenario is useful for overall characterisation of a link, but would be of much less use when trying to locate faults. A short pulse length will improve distance resolution of optical events, but will also reduce measuring range and attenuation measurement resolution. The “apparent measurement length” of an optical event is referred to as the “dead zone”. The theoretical interaction of pulse width and dead zone can be summarised as follows:

Miniature Spectrometers

Miniature Spectrometers
For Lasers, Laser Diodes, and LED

Experimental Setup for Laser, Laser Diode, and LED characterization using EPP2000-HR spectrometer with an IC2 integrating sphere and/or cosine receptor.

These instruments are used to measure wavelength emissions from Lasers, Laser Diodes and LED’s into the near infrared. A fiber optic cable is used to couple the output from the test device into the spectrometer. The instrument allows characterization of the wavelength stability with time, temperature, and device drive current. Depending on your application and wavelength requirements, StellarNet can offer high resolution spectrometers up to 0.1nm resolution. Contact StellarNet for availability of other wavelength range and resolutions.

Optional Configurations

Multi-channel systems for continuous monitoring of several devices are easily configured by daisy chaining additional units.

Optical Fibers

For 1310 and 1550nm laser diodes, a fiber is used to couple the ST device connector with an XNIR2 spectrometer input connector (SMA). Other couplings use a 400um fiber with a lens attached to a SMA bulkhead fitting that can be easily mounted in the device emission path.